During the assembly or packing of a motor or alternator which uses a toothed wheel mechanism, a coil which is wound around an insulator is inserted between two permanent magnet wheels which create the rotor. The coil, the insulator and the toothed wheels are coaxial devices. The insulator must be centred relative to the cores of the magnet wheels, and its rotation relative to the magnet wheels must be blocked. The coil must also be blocked in rotation around the axis of the insulator.
In the prior art, these functions were carried out by godroons. However, the production of parts comprising godroons is difficult to control. In addition, a device comprising godroons is difficult to assemble, since the two magnet wheels are guided by godroons. Also, the godroons have a small size, and their lateral surfaces prevent the rotation of the insulator relative to the magnet wheels. The lateral surfaces are thus subjected to high shearing stresses. In addition, the use of godroons prevents freedom of one magnet wheel relative to the other during the packing.